1. Field of the Invention
The present invention relates to a link mechanism for a carburetor.
2. Description of Background Art
As disclosed in JP-UM-A-61-167455, a link structure for activating an accelerator pump as a link mechanism for a carburetor is known.
FIG. 1 of JP-UM-A-61-167455 discloses a valve shaft 8 that is rotatably mounted to an upper body 2 of a carburetor, a throttle drum 10 is mounted to the valve shaft 8, a control cable 11 is wound around the throttle drum 10 and a distal end of the control cable 11 is mounted to the throttle drum 10. One end of a link rod 15 is connected to the throttle drum 10 and a distal end of a first arm 14 of an accelerator pump arm 13 is connected to the other end of the link rod 15 via a coil spring 16. A third arm 18 is provided on the side substantially opposite from the first arm 14 with respect to a swing axis of the accelerator pump arm 13. The third arm 18 is brought into abutment with an upper end of a push rod 19 which constitutes the accelerator pump. A diaphragm 24 is connected to a lower end of the push rod 19 with a discharge side channel 29 being connected to an accelerator pump chamber 21 in which the diaphragm 24 is stored and fuel is filled. An accelerator nozzle 32 projects from an inlet port 5 that is connected to an end of the discharge side channel 29.
When the control cable 11 is quickly pulled, the throttle drum 10 rotates, the link rod 15 is pulled, the coil spring 16 is compressed to swing the accelerator pump arm 13, the push rod 19 is moved downwardly to press the diaphragm 24 downwardly, and then fuel in the accelerator pump chamber 21 is injected from the distal end of the accelerator nozzle 32 via the discharge side channel 29 into the inlet port 5.
In case of the carburetor discussed above, since the link rod 15, the coil spring 16, and the accelerator pump arm 13 are provided integrally, in order to adjust the amount of fuel injection of the carburetor according to dimensional variations in manufacture or the like of the link rod 15, the coil spring 16 and the accelerator pump arm 13 to obtain an optimal value, replacement of the link rod 15 and so on is required.
As a countermeasure, the provision of an adjusting mechanism on a movement mechanism portion of the accelerator pump to optimize a density of air-fuel mixture at the time of acceleration is considerable. However, when the adjusting mechanism is exposed to the outside, a structure to prevent erroneous adjustment is required.